1. Field of the Invention
This invention relates to motion transmitting devices of the kind known as quadrant drive devices.
2. Prior Art
Quadrant drive motion transmitting devices, which may be used for speed changing, torque conversion and the like, are described for example in U.S. Pat. Nos. 4,023,440 and 4,194,415 (U.K. Nos. 1519588 and 1585961 ) and in U.K. Application No. 8011061. In conventional gearing arrangements, engagement is provided normally only by one tooth at a time. In the quadrant drive devices, meshing elements are employed which may remain in driving engagement with wheel means through a substantial fraction of a cycle; drive may be effective over nearly a quadrant of arc on the wheel means. Such devices essentially comprise eccentric means, wheel means and independently movable meshing elements the movement of which is controlled by movement limiting means so that the meshing elements move in and out of engagement with portions of the wheel means. Reference may be made to the abovementioned specifications for full descriptions of such devices. In U.S. Pat. No. 4,194,415, it is explained that the meshing elements may comprise links with two or more teeth, these being links of a chain. The present invention is directed to an improved form of quadrant drive motion transmitting device in which the meshing elements are independently movable and need not be linked in a chain but in which it is still possible to retain the high efficiency arising from pure rolling motion between relatively moving load-transmitting elements. As will be apparent from the following description, the present invention has particular advantages using a wheel with close-pitched teeth or a frictionally-driven wheel and hence enabling high torque or speed ratios to be obtained.